//list.html
<ul>
<li>1</li>
 <li>2</li>
 <li>3</li>
 </ul>
<script>
var ul = document.querySelector('ul');

ul.addEventListener('click', function(event) {

  // tagName
  if (event.target.tagName.toLowerCase() === 'li') {
    console.log('li')
  }
});</script>